PLAN B

Hello! So awhile back ago, I had a slip up with my SO, and we took plan B about 20 minutes after! Well I didn't have a period for 2-3 months after! And now my periods are all over the place. I will have them, and miss a month. Has anyone had issues with plan b messing them up? That was my first time taking it, and I haven't since then. But seriously, I haven't had an on scheduled period since like October!!!! Any recommendations?